Potentially exploitable segfault on pc

[strazzere]

Like the others, however this is potentially exploitable;

Starting program: /home/tstrazzere/repo/gifsicle/src/gifsicle -O2 segfaultonpc.gif --output /dev/null
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
gifsicle:./segfaultonpc.gif:#0: read error: image corrupted, min_code_size too big
gifsicle:./segfaultonpc.gif:#0: read error: image corrupted, code out of range (19 times)
gifsicle:./segfaultonpc.gif:#0: read error: (not reporting more errors)
gifsicle:./segfaultonpc.gif:#0: read error: missing 6528 pixels of image data
gifsicle:./segfaultonpc.gif:#1: read error: image corrupted, min_code_size too big
gifsicle:./segfaultonpc.gif:#1: read error: missing 1344 pixels of image data
gifsicle:./segfaultonpc.gif:#2: read error: image corrupted, min_code_size too big
gifsicle:./segfaultonpc.gif:#2: read error: image corrupted, code out of range (19 times)
gifsicle:./segfaultonpc.gif:#2: read error: (not reporting more errors)
gifsicle:./segfaultonpc.gif:#2: read error: missing 1214 pixels of image data
gifsicle: (plus more errors; is this GIF corrupt?)
gifsicle: warning: too many colors, using local colormaps
  (You may want to try ‘--colors 256’.)
gifsicle:./segfaultonpc.gif: warning: some colors undefined by colormap

Program received signal SIGSEGV, Segmentation fault.
-----------------------------------------------------------------------------------------------------------------------[regs]
  RAX: 0x0000000000000001  RBX: 0x00007FFFFFFFE170  RBP: 0x000000000063DDE0  RSP: 0x00007FFFFFFFE148  o d I t s z a P c 
  RDI: 0x0200000000000000  RSI: 0x00007FFFFFFFE170  RDX: 0x0000000000000001  RCX: 0x000000000000004A  RIP: 0x0000000000000000
  R8 : 0x0000000000000120  R9 : 0x0000000000000540  R10: 0x0000000000000005  R11: 0x0000000000000000  R12: 0x0000000000000001
  R13: 0x000000000063DDE0  R14: 0x000000000062D890  R15: 0x00000000006368F0
  CS: 0033  DS: 0000  ES: 0000  FS: 0000  GS: 0000  SS: 002B				Error while running hook_stop:
Cannot access memory at address 0x0
0x0000000000000000 in ?? ()
gdb$ exploitable
Description: Segmentation fault on program counter near NULL
Short description: SegFaultOnPcNearNull (12/22)
Hash: c74981be83a110625aad05cd34bea453.5a2d7afe30fd49135fa2a5afa7a89be1
Exploitability Classification: PROBABLY_EXPLOITABLE
Explanation: The target tried to access data at an address that matches the program counter. This may indicate that the program counter contents are tainted, however, it may also indicate a simple NULL deference.
Other tags: AccessViolation (21/22)

segfaultonpc.zip

[strazzere]

Appears to be mitigated by a0a3651